Field of the Invention
The present invention relates generally to a method for fabricating a layer structure constituted by a dielectric film containing a Si—N bond in a trench formed in an upper surface of a substrate.
Related Art
In manufacturing processes of large-scale integrated circuits (LSIs), there are several processes for forming sidewalls in trenches. The sidewalls are used as spacers or used for blocking etching of a structure from side surfaces of trenches. Conventionally, the sidewalls were formed by forming a conformal film on surfaces of trenches, and then removing portions thereof formed on an upper surface in which the trenches were formed and portions formed on bottom surfaces of the trenches by asymmetrical etching. However, when such a formation method is used, over-etching is required in order to remove footing of sidewalls in which the thickness of the sidewalls increases near and at the bottom, forming a slope. Over-etching causes etching of an underlying layer and causes damage to a layer structure.
Any discussion of problems and solutions in relation to the related art has been included in this disclosure solely for the purposes of providing a context for the present invention, and should not be taken as an admission that any or all of the discussion was known at the time the invention was made.